os: add mach VM tags

src/os/mach.zig

@@ -0,0 +1,35 @@
+const std = @import("std");
+
+/// macOS virtual memory tags for use with mach_vm_map/mach_vm_allocate.
+/// These identify memory regions in tools like vmmap and Instruments.
+pub const VMTag = enum(u8) {
+    application_specific_1 = 240,
+    application_specific_2 = 241,
+    application_specific_3 = 242,
+    application_specific_4 = 243,
+    application_specific_5 = 244,
+    application_specific_6 = 245,
+    application_specific_7 = 246,
+    application_specific_8 = 247,
+    application_specific_9 = 248,
+    application_specific_10 = 249,
+    application_specific_11 = 250,
+    application_specific_12 = 251,
+    application_specific_13 = 252,
+    application_specific_14 = 253,
+    application_specific_15 = 254,
+    application_specific_16 = 255,
+
+    // We ignore the rest because we never realistic set them.
+    _,
+
+    /// Converts the tag to the format expected by mach_vm_map/mach_vm_allocate.
+    /// Equivalent to C macro: VM_MAKE_TAG(tag)
+    pub fn make(self: VMTag) i32 {
+        return @bitCast(@as(u32, @intFromEnum(self)) << 24);
+    }
+};
+
+test "VMTag.make" {
+    try std.testing.expectEqual(@as(i32, @bitCast(@as(u32, 240) << 24)), VMTag.application_specific_1.make());
+}

src/os/main.zig

@@ -23,6 +23,7 @@ pub const args = @import("args.zig");
 pub const cgroup = @import("cgroup.zig");
 pub const hostname = @import("hostname.zig");
 pub const i18n = @import("i18n.zig");
+pub const mach = @import("mach.zig");
 pub const path = @import("path.zig");
 pub const passwd = @import("passwd.zig");
 pub const xdg = @import("xdg.zig");
@@ -73,5 +74,8 @@ test {
 
     if (comptime builtin.os.tag == .linux) {
         _ = kernel_info;
+    } else if (comptime builtin.os.tag.isDarwin()) {
+        _ = mach;
+        _ = macos;
     }
 }